Supplemental animal feedstuffs fortified with nutritive supplements have been developed in block form to permit free choice feeding and reduce the labor required for mixing the nutritive supplement with the animals' feed ration. Such nutritive supplement blocks may be of three types: poured blocks, low moisture blocks or pressed blocks.
Poured blocks require a curing agent for hardening, which may include magnesium oxide or another component that reacts in the presence of moisture. Upon pouring a liquefied nutrient supplement into a vessel, the mixture non-reversibly cures over a period of time, typically 24 hours. Skoch et. al., U.S. Pat. No. 4,171,385 describe molasses-based feed blocks wherein magnesium oxide is employed as an ingredient to form a pourable heated composition that self-hardens after cooling into a solid, weather resistant feed block suitable for ruminant consumption. Such feed blocks have the advantage of ease of manufacture, since pourability is provided and hardening of the block occurs without the need to evaporate water, leading to lower manufacturing costs and lower energy consumption in the finished product compared to blocks where water evaporation is necessary.
Pressed blocks are typically formed by heating and adding steam to dry feed under high pressure conditions. The pressure exerted on the supplemental animal feedstuffs and binders such as lignin are responsible for binding the feed components together and enables the block to retain its shape.
Low moisture blocks require dehydration or moisture removal for hardening. This type of block is also referred to as a cooked tub because the nutritive supplement mixture is “cooked” and upon pouring into a vessel, e.g., a tub, the contents are allowed to cool and harden into a block. Such blocks contain molasses as a primary component at a level of 40 wt % or higher.